Combination dye-stripper



meme Apr. 20,. 1937 UNITED STATES.

2.071.983- cormimnon nmsmmrnn David Julian Block, Wlnnetka, lll., assignor to Hobart M. Cable No Drawing. Application July 17, 1935, Serial No. 31,947

. 12 Claims. This invention relates to dye-strippers, and

not only may need both, but at any rate seldom can tell which is necessary. Likewise in the com- 15 mercial stripping of waste materials, as in the manufacture of shoddy, it is essential that the.

stripper have both actions.

It has now been discovered that a stripper ca.- pable of acting upon botht'ypes of dye may be readily prepared by providing a compound which will form an oxidizing bath upon its initial solution, and may then by a simple operation, suchas heating, activate a latent reducing agent contained in the compound. This may be accom- 25 plished, for example, by providing a stripper containing an oxidizing agent immediately available in cold water, together with a latent reducing agent, active only at high temperatures. This lack of activity may be normal to the agent, or

30 it may be artiflcally effected by other materials.

For example, the reducing agent may be rendered latent by coating it with wax, so that it does not become active-until the solution has been heated to the melting point of the wax.

3 Obviously-the reducingagentfiay be rendered latent by her means, and may be activated by temperature, time, or other agents.

,In accordance with the invention, a reducing stripper is thoroughly mixed with enough molten.

40 wax, or the" like, to cover it, and this is solidified and subdivided, or ground, and is then mixed with an oxidizing agent. In carryingout the process, the stripper is added to-water or other solvent, and the mixture is gradually heated. The oxi- 45\ dizing stripper commences its work at low temperatures, and at higher. temperatures the reducing agent is activated, neutralizes any remaining oxidizing agent, and then strips the remaining dye.

. 50 While any efiective reducing agent may be used,

,it is preferred to use the reducing agent-disclosed.

in my co-pending application Ser. No. 737,313, filed July 27 1934. This stripper consists of two parts of basic zinc sulfoxylate formaldehyde, two 55 parts of sodium hydrosulfite, (NaaSzOO; 1%

parts of sodium bisulfite, preferably together with parts of monocalcium phosphate. To this is added 1% parts of monocalcium phosphate to neutralize residual alkalinity of the oxidizing agent. This additional monocalcium phosphate may, of course, be replaced by other acidic materials, such as formic acid, citric acid or the like. The reducing agent, preferably in powdered form, is then placed in molten wax, as for example paraffin, carnauba wax, or the like. After the 10 mixture has solidified, it is cut or ground as desired, and mixed with a suitable oxidizing agent. Any known oxidizing agent, of which sodium perborate is preferred, may be used. Preferably the oxidizing agent should be active at low temperatures, since otherwise .the inactivating agent must be able to stand high temperatures. The sodium perborate does not become active until a somewhat higher temperature has been reached, and if used alone, it is preferred to use carnauba wax as a protector for the latent reducing agent. However, the sodium perborate may be catalyzed by the addition of a very small quantity of a manganous salt. It is preferred to use about onetenth of 1% of manganous chloride, based upon the weight of the perborate usedffThis enables the oxidation to proceed at low temperatures, and

I it is therefore possible to use low melt point panafiin, dextrine, glue, or even sparingly soluble salts, as protective agents for the reducing agent.

Other known perborate catalysts, such as ferrous 0 or cobaltous salts, may be used, but are not so I effective as the manganous.

About 7 parts of the waxed reducing agent is mixed with 4 parts of sodium perborate. On the basis of the reducing agent dissolved, this amounts to about 6 parts of reducing agent per 4 parts of oxidizing agent.

In place of the wax, it is possible to use gelatine, or some other material adapted to dissolve 40 at or near the boiling point of water. Likeudse, acids such as mucic, having a very low solubility at low temperatures, and considerable solubility\' at higher temperatures, may beused. In such case a reducing stripper is used which is inactive 5 in alkaline solution, and an alkaline oxidizing agent is used. The specific example given shows such a reducing stripper.

An acid has a particular value in producing t-ie desired conditions for reduction upon its ultimate solution.

In carrying out the process, it is preferred to add 1 to 15 parts of the combined mixture to 100 parts of cold water, and the fabric is then placed in this mixture, and the solution gradually heated.

As a further feature of the invention, a vat dye, or other dye unafiected by the strippers used, may be combined with them simultaneously to produce a new color on the stripped fabric. Owing to the extreme efficiency of the combined strippers, very fine and even light colors may be imposed upon fabrics previously having entirely difierent colors.

This invention may likewise be applied in connection with the stripping of any material requiring treatment with two or more chemically incompatible baths. limited to the use of first, an oxidizing, and then a reducing bath, but may be applied to baths in the opposite order, and likewise may be applied to baths which are first acid and then alkaline, or vice versa.

Following are examples of certain types of combination dye-stripping baths, in each of which an active stripping bath is first established, and then a chemically incompatible stripping bath is produced by the activation of an inert ingredient or ingredients.

The various inactivating agents have not been specified in. each case, but ordinarily the latent material will be inactivated by a coating of wax, as already described.

In many instances, where economy is desired, the acid or basic agents in the active baths may be made volatile so that it can be removed by the time the latent material has been activated.

Acid oxidizing Parts Soda perborate (NaBO3-4H2O) 2 Nitre cake (NaHSOi) 3 Mono calcium phosphate (CaH4(PO4)2'HzO)-.. 1 1 Alkali reducing Parts Sodium sulphoxylate formaldehyde (NaHSOzCI-IzO-ZHzO) 3 Sodium Hydroxide (NaOH) 3 I I Alkali oxidizing Parts I Soda perborate (NaBO3-4H2O) 4 Acid reducing Parts Zinc sulphoxylate formaldehyde (basic) (Zn(OH)HSO2CH2O) 2 Sodium hyposulphite (Na-2S2Os-5HzO) 2 Sodium bisulphite (NaHSOa) 1% Mono calcium phosphate (CaH4(PO4)2-H2O) Alkali reducing Parts Sodium sulphoxylate formaldehyde (NaHSO rCHZO-ZHQO) 3 Sodium hydroxide (NaOH) 3 Acid oxidizing Parts Soda perborate (NaBO3-4H2O) 2 Nitre cake (NaHSQD 3 Mono calcium phosphate (CaHAPODa-HzO) 1 Acid reducing Parts Zin'c sulphoxylate formaldehyde, basic ZD(OH)HSO2CH2O) 2 Sodium hyposulphite (NazSzOa-EHaO) 2 Sodium bisulphite(NaHSOa) 1V Mono calcium phosphate (Cal-IMPOOz-HaO) Thus, the invention is not Mono calcium phosphate (CaH4(PO-i)z.HzO) 1 The term stripper as used herein applies not only to the stripping of dyes, but to bleaching of dyed or undyed materials as well. I This description is given for clearness of understanding only, and no unnecessary limitationsshould be understood therefrom, but the appended claims should be construed as broadly as permissible in view of the prior art.

This application is a continuation in part of my co-pending application,, Serial No. 737,314, filed July 27, 1934.

What I- claim as new and desire to secure by Letters Patent is: I 1. The method of dye-stripping which comprises subjecting 'materials to be stripped to a dye-stripping bath comprising an active oxidizing stripper and a latentreducing stripper, where- 'by the oxidizing stripper acts upon said material, subsequently activating the reducing stripper, and treating said material with said activated reducing stripper.

2. The method as set forth in claim 1, in which Alkali oxidizin Parts Soda perborate (NaBO34HzO) 4 No. 5 Alkali oxidizing Parts Soda perborate (NaBOa-4H2O) 4 Alkali reducing Parts Sodium sulphoxylate formaldehyde (NaI-ISOzCH2O-2HzO) 3-. Sodium hydroxide (NaOH) 3 No. '6 Alkali reducing Parts Sodium sulphoxylate formaldehyde (NaHS0iCH2O-2H2O) 3 Sodium hydroxide (NaOH) 3 Alkali oxidizing Parts Soda perborate.(NaBOa-4Hz0) 4' Acid oxidizing Parts Soda perborate (NaBOaAI-IaO) 2 Nitre cake (NaHSOQ 3 Mono calcium phosphate (CaHdPOr) 2.1120)" 1 Acid reducing Parts zinc sulphoxylate formaldehyde, basic (Zn(OH)HSOzCI-I2O) 2 Sodium hyposulphite (NazSzOa.5H20) 2 Sodium bisulphite (NaHSOa) 1 Mono calcium phosphate (CaH4(PO4) 2.1120) Acid reducing Parts Zinc sulphoxylate formaldehyde, basic (Zn(OH)HSOaCH2O) 2 Sodium hyposulphite (NazSzOa.5HzO) 2 Sodium bisulphite (NaHSOa) 1 Mono calcium phosphate (CaHdPOr) a.Ha0)

Acid oxidizing Parts Soda perborate (NaBOaAHaO) 2 Nitre cake (NaHSO4) 3 dered inactive by a waxy coating, wh re'py the loox'idizing stripper acts upon said mater al, heat:

ing said bath to melt said waxy coating and activate said reducing agent, and stripping said ma-- terial with said-activated reducing stripper.

4. The method set forth in claim 3, in which 15 the oxidizing stripper is an alkali metal perborate,

and said stripper is catalyzed by a small proportion of a manganous salt.

5. A dye-stripper comprising an active oxidizing stripper and a latent reducing stripper.

20 6. A dye-stripper comprising an active oxidizing stripper and a reducing stripper rendered latent by a protective coating.

\ 7. A dye-stripper comprising an active oxidizing stripper and a reducing stripper having a 25 waxy coating thereon.

8. A dye-stripper comprising an alkali metal perborate, a small proportion of a manganous salt, and a latent reducing stripper.

9. A dye-stripper comprising sodium perborate with a small proportion of a manganous salt, and a latent acid reducing agent containing suflicient excess acid to neutralize the perborate.

10. A combined oxidizing and reducing dye stripper comprising sodium perborate; a small proportion of manganous chloride, together with a reducing stripper comprising zinc sulfoxylate formaldehyde, sodium hyposulfite, sodium bisulflte, and monocalcium phosphate, said reducing stripper being coated with an inactivating material.

11. The method of dye-stripping in a singl bath a material requiring both an oxidizing and a reducing treatment which comprises subjecting such material to a stripping bath comprising an active dye-stripper of one of said types, and a latent dye-stripper of the other type, and subsequently activating the latent material and continuing the treament in the activated material.

12. A dye stripper for dye-stripping in a single bath a material requiring both an oxidizing and a reducing treatment which comprises an active dye-stripper of one of said types, and a latent dyestripper oi the other type.

DAVID JULIAN BLOCK. 

